The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Landfill gas wells typically have a port component to which an external gas flow rate sensing device may be temporarily attached. Typically these port components make use of one or more barbs formed on an outer surface of the port. An elastomeric cap component is slid over the port component to close off the port thereof. When a technician needs to check the gas flow through the wellhead, the cap component is slidably removed from the port component and an external rubber or plastic hose is attached to the port component. An opposite end of the hose is connected to an external gas quality, pressure and flow measurement device. When the technician is done making the gas (flow) measurements he/she would typically remove the hose that was used with the measurement device, and slide the cap component back over the barbs on the port component. Thus, the barbs sealing with the inside surface of the cap component is how a seal is achieved.
The above arrangement of a cap component making contact with the barbs on the port component has some drawbacks. For one, to achieve satisfactory sealing, there has to be an extremely tight fit between the cap component and the barbs, since this is where the actual sealing takes place. This often requires such a tight fit that the cap component can be difficult to slide on and off the port component. This is especially true in cold climates, where the rubber or plastic cap component may lose some of its stretchability. The very tight fit required also can result in rapid wear of the material on the inside surface of the cap component where contact with the barbs is made, which can lead to leaks of atmospheric air into the vacuum condition in the landfill gas collection wellhead and thereby degrade the energy and reuse value of the recovered gas. And the wear may not be that noticeable to the technician, so the possibility arises that the cap component inner surface may not be making a perfectly air tight seal with the port component, but this fact is not immediately detectable by the technician.
Still another drawback is that present day cap components used with wellhead structures are not able to seal an orifice of the port component to prevent freezing and blockage of the orifice during the winter months in cold climate areas. Freezing occurs when condensation occurs in the orifice and the condensation freezes. When this occurs, a technician must spend extra time unblocking the orifice before measurements can be taken through the port component. A cap assembly that can help prevent freezing and blockage of the orifice of the port component would therefore be highly desirable.